A slice of pork belly, with a thick layer of fat. "If we confirm that fat is a basic taste quality, it's the equivalent of saying chartreuse is a primary color," Richard Mattes of Purdue University says. "It changes our basic understanding of what taste is."

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Your tongue doubtless knows the difference between a high-fat food and the low-fat alternative. Full-fat ice cream and cream cheese feel silkier and more sumptuous. Burgers made with fatty meat are typically juicer than burgers made with lean meat.

OK, so, we've long known fat gives food a desirable texture. But some scientists are now making the case that we should also think of fat as the sixth primary taste, along with sweet, salt, sour, bitter and umami.

Early in February, researchers from Deakin University in Australia published a paper in the journal Flavour arguing that "the next 5 to 10 years should reveal, conclusively, whether fat can be classified as the sixth taste."